The present invention relates generally to clamping devices and, more particularly, to clamping devices for railway rails.
A conventional railway track includes a pair of elongated running rails that receive the wheels of train cars thereon. The running rails are spaced laterally apart from one another and extend longitudinally and in substantially parallel relation to one another. For electric-powered train cars, such as subways and the like, a third rail is located adjacent to one of the running rails and is energized with electrical current and serves as the power supply for the electrical motors of electric-powered train cars. Electric-powered train cars typically have one or more steel collector shoes that contact the top portion of a contact rail for transferring electrical current from the contact rail to a train car""s electric motors.
FIG. 1 illustrates a conventional arrangement of railway running rails 10 and an adjacent contact rail 12 for supplying electrical power. The contact rail 12 rests on elevated insulators 13 that are spaced apart along the railway. The wheels 14 of a train car engage and roll along the running rails 10 and a collector shoe 16 is in contact with the top portion 12a of the contact rail 12 and receives electrical power therefrom.
Because electrically energized contact rails are dangerous, a protection cover 18 is conventionally utilized as illustrated in FIG. 1, particularly in areas where passengers may be present, such as loading platforms, etc. A protection cover 18 is conventionally mounted over the top portion 12a of a contact rail 12, as illustrated. Conventionally, a gap of about 3 inches is provided between the top portion 12a of a contact rail 12 and the bottom 18a of a protection cover 18. However, this gap may vary. Conventionally, contact rail protection covers are permanently attached and cannot be removed, even for maintenance on the contact rail.
During railway maintenance work (e.g., replacing old or damaged rails, electrical circuit rewiring, construction, etc.), a contact rail is conventionally discharged or grounded once the electrical power is turned off. Conventionally, grounding of a contact rail is accomplished by connecting an electrical cable between the contact rail and the running rail farthest away from the contact rail.
Unfortunately, the confined space between a contact rail and an overlying protection cover may make it difficult to apply a conventional clamp (e.g., a xe2x80x9cC-clampxe2x80x9d) to the contact rail. Accordingly, railway maintenance crews typically employ a xe2x80x9chomemadexe2x80x9d clamping device that is configured to clamp on to a contact rail as illustrated in FIG. 2. The illustrated clamping device 20 includes an electrically conductive xe2x80x9chook-upxe2x80x9d pad 22 (e.g., a copper pad) with a chain 24 and a T-handle 26. The hook-up pad 22 is placed on the top portion 12a of a contact rail 12 and is held in place via a U-shaped holder 23 and a chain 24. The chain 24 is tightened around the pad holder 23 and the contact rail 12 via the T-handle 26. An electrical cable 28 extends from the clamping device 20 to a clamping device 30 attached to a running rail 10. The contact rail 12 is grounded to the running rail 10 via the electrical cable 28.
Unfortunately, installation of conventional clamping devices on contact rails can be time consuming and inconvenient. Moreover, conventional clamping devices can be dangerous because a person installing the clamping device may be required to come very close to an energized contact rail. This may be hazardous even if the person is wearing required protective clothing. Accordingly, there is a need for clamping devices that are quick and easy to install on energized contact rails protected by overhead covers and that can reduce the chances of operator exposure to an energized contact rail.
In view of the above discussion, hand-held tools for gripping a railway contact rail to facilitate grounding thereof are provided. According to embodiments of the present invention, a hand-held tool includes first and second members pivotally attached. The first member includes a first jaw at an end thereof, a handle at an opposite end thereof, and a first intermediate portion extending between the first jaw and the handle. The second member includes a second jaw at an end thereof, a set of ratchet teeth at an opposite end thereof, and a second intermediate portion extending between the second jaw and the set of ratchet teeth. The first and second jaws are configured to pivot towards each other and grip respective opposite sides of a railway contact rail when the handle is pivoted in a downwardly direction.
According to embodiments of the present invention, a pawl extends from the first intermediate portion and engages the set of ratchet teeth to hold the first and second jaws in contact with the respective opposite sides of a railway contact rail. A spring operatively associated with the pawl is configured to urge the pawl into engagement with the set of ratchet teeth. A release lever operatively associated with the biasing member and/or the pawl is configured to disengage the pawl from the set of ratchet teeth and to allow movement of the handle so that the first and second jaws can be disengaged from the contact rail.
According to embodiments of the present invention, one or more roller members may be located at the first and second jaws to facilitate installation of the hand-held tool on a contact rail.
Hand-held tools according to embodiments of the present invention can operate within very narrow spaces, thus allowing operators to quickly and easily grip an energized contact rail protected by an overhead protection cover while maintaining a safe distance therefrom.